Irritable bowel syndrome (IBS) is a common gastrointestinal disorder that is characterized by recurrent[unreadable] abdominal pain and disturbance in bowel movements. The exact mechanism of IBS is poorly understood but[unreadable] mounting evidence suggests that visceral hyperalgesia and psychosocial stress play important roles in the[unreadable] pathogenesis. Serotonin (5-HT) is abundant in gastrointestinal tract and one of the major neuropeptides[unreadable] involved in pathogenesis of IBS. In rodent models, persistent visceral hyperalgesia in the adulthood can be[unreadable] induced by stressors during neonatal period such as neonatal maternal separation and rectal balloon[unreadable] distension. We have previously reported that early life stressors can lead to enhanced responsiveness of[unreadable] serotoninergic pathway in enteric nervous system. Theoretically, visceral hyperalgesia and irritable bowel[unreadable] syndrome may be treated by reversal or inhibition of enhanced activity of serotoninergic pathway.[unreadable] Unfortunately, medical treatment of IBS has been disappointing. Although a few 5-HT receptor modulators[unreadable] are marketed for treatment of IBS in recent years, there has been concern about the safety of these drugs.[unreadable] On the other hand, acupuncture has been used extensively for treatment of various painful conditions and[unreadable] gastrointestinal diseases in Traditional Chinese Medicine. According to Chinese medical theories, the most[unreadable] common cause of IBS is the "stagnation of liver energy attacking the spleen and resulting in dysfunction of[unreadable] the transportation and transformation function of the spleen". This is a condition characterized by a syndrome[unreadable] of recurrent abdominal pain, diarrhea and psychological conditions such as depression and anxiety. Based[unreadable] on the principle of TCM, as mentioned in the Yellow Emperor's Inner Classics, the most ancient TCM medical[unreadable] book, one should "use herbs to treat the illness internally and acupuncture to treat externally".[unreadable] Our previous studies have revealed that electroacupuncture (EA) produces prolonged anti-inflammatory and[unreadable] anti-hyperalgesic effects in rats with complete Freund's adjuvant (CFA)-induced inflammatory hyperalgesia. It[unreadable] has been reported that EA-induced anti-inflammation-and anti-hyperalgesia involves modulation of functions[unreadable] in the neuroendocrine system including serotoninergic system. Thus, acupuncture may be a promising[unreadable] treatment for IBS.[unreadable] [unreadable] The objective of this study is to evaluate the visceral anti-hyperalgesic effect of EA and its mechanism in a rat[unreadable] model of visceral hyperalgesia. We hypothesize that EA modulates the central processing and peripheral[unreadable] signaling functions in visceral nociceptive pathways, and thereby alleviates visceral hyperalgesia. The specific[unreadable] aims of the study are:[unreadable] 1. To determine the effect of EA on behavioral and visceromotor response to visceral pain in rat model of[unreadable] visceral hyperalgesia.[unreadable] 2. To determine the effect of EA on colonic mucosal serotoninergic signaling in rats with visceral[unreadable] hyperalgesia.[unreadable] 3. To determine the effect of EA on serotoninergic activites at spinal cord level in rats with visceral[unreadable] hyperalgesia.[unreadable] 4. To determine the effect of EA on serotoninergic activites in dorsal raphe nucleus and raphe nucleus[unreadable] magnus, the relay centers of central descending inhibitory pathway, in rats with visceral hyperalgesia.[unreadable]